When the 102 bus travelling from East Finchley towards Muswell Hill arrived, the victim boarded but the suspect did not follow her.

Kieran Nagle, 32, who has lived in Fortis Green for four years, said: “It’s horrible when anything like that happens to a girl – but to an elderly, vulnerable woman, it's just shocking. Whoever did it is disgusting.

“I can’t believe this has happened just across the street. I never thought anything like that would happen in East Finchley because it’s such a nice area.”

Klaus Zirngibl, who has lived in Fortis Green for a year and a half, said: “It’s really scary – I normally feel safe around this area. It’s just terrible.”

And neighbour Richard Morris agreed it was “very unusual” for an attack like this to happen in the area, especially on such a busy residential street with a high number of cars driving by.

Meanwhile East Finchley ward Councillor Arjun Mittra has said the incident has “shocked the community”.

He said: “It’s an extremely shocking incident. We don’t often hear of these kinds of crimes in the area. My heart goes out to the lady and her family.”

And Liberal Democrat Crime spokesman and councillor for Fortis Green, Martin Newton, said: “This awful attack is very concerning. I hope that the police will swiftly find the perpetrator.”

Police are calling for witnesses as they attempt to track down the suspect who is described as a black man, who is approximately 30-years-old.

At the time of the incident he was wearing a thick, dark coloured coat with a logo on the right sleeve and light blue jeans. He also wore a hood or a hat and a scarf.

Detective Constable Alex Peddie said: "This attack took place in daylight on a very busy road. Were you in the area at the time of the assault or were you travelling on the route 102 as it pulled into the stop on Fortis Green? If you saw anything and can assist this investigation, please contact police."